Patients treated for Merkel cell carcinoma face a 5-year recurrence rate of 40%—markedly higher than the recurrence rates for melanoma and other skin cancers, according to research published by McEvoy et al in JAMA Dermatology. Additionally, in the study cohort of more than 600 patients, 95% of Merkel cell carcinoma recurrences happened in the first 3 years, suggesting that surveillance efforts should be focused on that time span, according to the study authors.
“Merkel cell cancer is a life-changing diagnosis. It can be time-consuming, costly, and exhausting to undergo clinic visits, imaging studies, and blood draws. Now we have data on the time intervals and cancer stages that merit higher or lower surveillance intensity,” said Aubriana M. McEvoy, MD, MS, who led the research while she was at the University of Washington School of Medicine. She is currently a dermatology resident at Washington University in St. Louis.
Merkel cell cancer is a rare, aggressive skin cancer, more often fatal than invasive melanoma and basal cell and squamous cell carcinomas. Merkel cell carcinoma is composed of cells that look very similar to healthy Merkel cells that are a key part of the epidermis, the skin’s outer layer. Normal Merkel cells communicate touch-related information such as pressure and texture to the brain.
Study Results
This study comprised 618 patients (37% female) whose ages ranged from 11 to 98 years (median age = 69). In this cohort, initial treatment (surgery, radiation, and systemic therapy) had a median duration of 90 days.
The authors sought to characterize posttreatment recurrence risk of Merkel cell carcinoma diagnosed at pathologic and clinical stages. Risk of recurrence at 1 year was found to be:
- 11% among patients diagnosed with stage I disease
- 33% among patients diagnosed with stages IIA/IIB disease
- 30% among patients diagnosed with stages IIIA disease
- 45% among patients diagnosed with stage IIIB disease
- 58% among patients diagnosed with stage IV disease.
The investigators found four factors associated with a higher recurrence risk: advanced age, male sex, immunosuppression, and a known primary lesion amid clinically detectable nodal disease.
As expected, survival among cohort patients was strongly dependent on cancer stage at time of diagnosis: the Merkel cell carcinoma–specific survival rate at 5 years post-treatment was 95% for patients diagnosed at stage I vs 41% for patients diagnosed at stage IV.
Merkel cell carcinoma survival “is a more accurate measure of disease risk than overall survival,” the authors wrote, because patients, with a median age of 70 at diagnosis, are at “considerable” risk of death from conditions unrelated to cancer. Again, stage at diagnosis was associated with a meaningful difference: 90% of deaths among patients with stage IV disease were attributed to Merkel cell carcinoma, whereas just 57% of deaths among patients diagnosed at stage I were attributed to the disease.
“This is a tricky cancer to beat because it comes back after optimal therapy in almost half of patients. We want to help patients figure out how much remaining risk of recurrence they have at various times after diagnosis,” said senior study author Paul Nghiem, MD, PhD, Chair of Dermatology at the University of Washington School of Medicine.
He added that the University of Washington’s database is likely the most comprehensive anywhere for Merkel cell carcinoma case therapies and outcomes.
“These are all patients who were followed meticulously to know why they’re doing well or not doing well. The size of the data set has allowed us to see patterns more clearly, and we need data to drive optimal decision-making,” Dr. Nghiem said.
Disclosure: This research was supported by funding from the National Institutes of Health/National Cancer Institute, the MCC Patient Gift Fund, and the Kelsey Dickson Team Science Courage Research Team Award from the Prostate Cancer Foundation. For full disclosures of the study authors, visit jamanetwork.com.
